27 Dezember 2006

Rapeseed oil used as fuel causes extremely high cancer risk

Some less pleasant news is coming from the Berufsgenossenschaftliches Forschungsinstitut für Arbeitsmedizin (BGFA) at the Ruhr-University of Bochum, Germany. Scientists at this institute of research for health protection at the workplace have found that the exhausts of rapeseed oil used as a fuel in internal combustion engines increases cancer risks 10-fold compared to the exhausts from regular diesel or biodiesel. (Download the study here (language: German))

Rapeseed oil, or canola oil as it is known in leading producer Canada, is a widely used feedstock for the production of biodiesel. But the oil can be used in diesel engines in its pure, cold-pressed form too. More and more large transport firms are switching to using exactly this pure plant oil (PPO), because it is considerably cheaper than biodiesel.

Especially in Germany, PPO is used extensively, mainly because a thriving industry developed over the years which converts diesel engines in a very efficient and affordable way to make them run on rapeseed oil.

In a first series of analyses, Dr Jürgen Bünger’s research team compared the emissions from burning petroleum diesel, biodiesel and rapeseed PPO in a diesel engine, and their damaging effects on genetic material. These effects are an indirect indicator of the cancer-inducing potential of the toxic fumes.

They noted that for both petro-diesel and biodiesel, the cancer-inducing potential was relatively low, whereas that of pure rapeseed oil was 10 times higher. At first, the scientists believed that the high viscosity of the plant oil was to blame for this dramatic result:

To find out, they carried out similar tests on a type of rapeseed oil that was treated in such a way that its viscosity was lower. The results were surprising: the cancer potential of this type of oil was 30 times higher than that of diesel and biodiesel. “A completely unexpected result”, says Dr Jürgen Bünger, “which proves that the viscosity of the oil can not be the determining factor”.

The scientists are now trying to find the precise causes of the large difference between rapeseed oil and its alternatives in a new project. Because the research is complex but important for public health, engineers, medical scientists and chemists from the BGFA, the University of Göttingen, the Bundesforschungsanstalt für Landwirtschaft (the German agency for agricultural research) and Coburg College have teamed up.

One thing is certain: the use of pure rapeseed oil as a transport fuel is a health hazard to all employees who drive such vehicles on a daily basis and who are exposed to the exhausts. Workplaces where diesel engines fueled by PPO are operated, and that are not well aerated, should be considered to be dangerous as well. In such places, workers are directly exposed to the cancerogenous fumes.

The researchers show that products carrying the “bio”-label must be carefully screened on their health risks.

We might add that several other types of plant oil are being used in their pure form as a transport fuel and for electricity generation in diesel gensets, most notably jatropha oil. As far as we know, there has been no research into the potential cancer risks associated with the use of this fuel. Jatropha oil is mainly utilised in the developing world, albeit on a small scale.